Regulation rule of cellulose nanocrystals on thixotropy of hydrogel for water shutoff in horizontal wells

Water production limits the efficient development of horizontal wells. But the ordinary hydrogel cannot completely fill the annulus between the wellbore and slotted liners due to poor thixotropy, which determines that the water cannot be successfully plugged. In this paper, cellulose nanocrystals (CNC) were applied to develop a hydrogel with high thixotropy for water shutoff in horizontal wells. Besides, the effect of CNC concentration, inorganic salts concentration, and temperature on thixotropy was observed, respectively. The results indicate that the thixotropic feature is enhanced by increasing the concentration of CNC. The CNC is an effective thixotropic regulator. The hydrogel has the highest thixotropy when the CNC concentration is 10%. The inorganic salts concentration will reduce the thixotropic performance of the hydrogel. This is maybe because NaCl and CaCl2 as strong electrolytes could be fully hydrolyzed into Na+ and Ca2+, which will reduce the water activity of the hydrogel. The introduction of NaCl and CaCl2 will reduce the thixotropic performance due to Na+ and Ca2+ are associated with the group bridge in the hydrogel components, which makes the molecular gel chains entangled with each other. What's more, the Ca2+ in CaCl2 plays a more critical role in increasing the degree of freedom of water molecules in the hydrogel compared to NaCl. The improvement of CNC concentration is advantageous to reduce the influence of inorganic salts concentration. The effect of temperature on thixotropy was observed at 50 degrees C, 60 degrees C, 70 degrees C, and 80 degrees C, respectively. The results show that the high temperature has a negative influence on thixotropy of CNC hydrogel. This is because the CNC hydrogel is a three-dimensional grid structure formed by intermolecular hydrogen bond interactions of CNC molecules. But the hydrogen bond between CNC molecules is easy to break when the temperature rises. The increase of CNC concentration can reduce the impact of temperature. The study could enrich the regulation theory between nanoparticles and polymers. It also provides technical guidance for further increasing the thixotropy of enhanced oil recovery (EOR) polymers, such as drilling fluid and fracturing fluid commonly used in petroleum industry

Lateral Pressure Test of Vertical Joint Concrete and Formwork Optimization Design for Monolithic Precast Concrete Structure

When the vertical joints of monolithic precast concrete structures are cast by self-compacting concrete, the design of the formwork under rational lateral pressure of self-compacting concrete becomes a key technical issue. In this paper, a prototype simulation test was conducted for the pouring of self-compacting concrete in the vertical joint of precast concrete walls. The self-compacting concrete was continuously poured from the top of vertical joints with a height of 2.8 m without any assistance such as a delivery tube. The formwork pressure of self-compacting concrete was measured at different heights with varying casting time. Results showed that the lateral pressure increased with the increase in slump-flow of fresh self-compacting concrete, reaching a peak value of about 70 kPa at a height of about 600 mm from the bottom of formwork. Compared to the concrete with a slump-flow of 550 mm, the self-compacting concrete with the slump-flow reached 655 mm and 755 mm, presenting an increase in the peak lateral pressure by 31.5% and 44.9%, respectively. A method for calculating the lateral pressure of self-compacting concrete on the joint formwork is proposed using the analysis of enveloped test curves. Under the condition with enough strength and limited deformation of the joint formwork, the optimal design of aluminum alloy formwork is determined using finite element analysis. This provides a sci-tech foundation of the optimal design to lighten the weight of joint formwork to improve the installation efficiency and reduce the manual power cost

Study on out-of-plane shear behavior of new tubular roof prefabricated structures

The tubular roof prefabricated (TPR) structures consist of steel tubular roof and reinforced concrete. To make full use of tubular roof materials in the structures, the TPR structure is innovated by replacing stirrups with tie bars. This paper performed tests on two specimens with transverse reinforcement ratio as parameter to investigate the shear behavior of new TRP structure members. The results show that the number of transverse reinforcement influences the members’ failure model and shear-bearing capacity. Three-dimensional finite element (FE) models were developed to simulate the shear behavior of new TRP members, and the FE results were in good agreement with the experimental results in the tests. Based on this model, the sensitivity of different factors on the shear performance of new TRP members were analyzed. The main influencing factors were determined, and the suitability of the shear capacity calculation formulas in different codes for new TRP structure members is verified

Mendelian randomization of chronic hepatitis B and cardiovascular disease

BackgroundEvidence from observational studies suggests that chronic hepatitis B (CHB) is associated with cardiovascular disease (CVD). However, results have been inconsistent and causality remains to be established. We utilized two-sample Mendelian randomization (MR) to investigate potential causal associations between CHB and CVD, including atherosclerosis, coronary heart disease, hypertension, and ischemic stroke.MethodsThe analysis was conducted through genome-wide association studies (GWAS), considering chronic hepatitis B as the exposure and cardiovascular disease as the endpoint. The primary method for evaluating causality in this analysis was the inverse-variance weighted (IVW) technique. Additionally, we employed the weighted median, MR-Egger regression, weighted mode, and simple mode methods for supplementary analyses. Finally, heterogeneity tests, sensitivity analyses, and multiple effects analyses were conducted.ResultsIn a random-effects IVW analysis, we found that genetic susceptibility to chronic hepatitis B was associated with an increased risk of atherosclerosis [OR = 1.048, 95% CI (1.022–1.075), P = 3.08E-04], as well as an increased risk of coronary heart disease [OR = 1.039, 95% CI (1.006–1.072), P = 0.020]. However, it was found to be inversely correlated with ischemic stroke risk [OR = 0.972, 95% CI (0.957–0.988), P = 4.13E-04]. There was no evidence that chronic hepatitis B was associated with hypertension [OR = 1.021, 95% CI (0.994–1.049), P = 0.121].ConclusionOur research indicates that chronic hepatitis B has a correlation with an elevated risk of developing atherosclerosis and coronary heart disease, while it is associated with a decreased risk of experiencing an ischemic stroke

Diabetes distress as mediators of loneliness and health promotion behaviour: a cross-sectional study

Objectives The purpose of this study was to explore whether diabetes distress mediated the relationship between loneliness and health promotion in older adults with diabetes.Design A cross-sectional study.Setting The study was conducted at three tertiary hospitals in Changsha, Hunan Province, China.Participants The sample included 140 patients with diabetes (65 years and older, mean age 72.6 years, SD=4.6).Methods We employed path models to analyse data on diabetes distress, loneliness and health promotion behaviours. We collected diabetes distress, loneliness and health promotion behaviour with self-reported questionnaires including the Diabetes Distress Scale, the University of California at Los Angeles (UCLA) Loneliness Scale and the Elderly Health Promotion Scale from January 2022 to October 2022. Mediation analysis was performed by SPSS V.26.0’s PROCESS macro.Result The findings of this study indicated diabetes distress acted as a mediator between loneliness and health promotion behaviour. According to bootstrapping results, the total effect of loneliness on health promotion behaviour was significantly negative (β=−0.312, p=0.006). Loneliness significantly and negatively correlated with diabetes distress (β=−0.043, p<0.001), while diabetes distress significantly and negatively correlated with health promotion behaviours (β=−2.724, p=0.008). Both the indirect effect and the direct effect of loneliness on health promotion behaviour were significant.Conclusion Our study illustrated that loneliness was negatively associated with health promotion behaviours, and diabetes distress acted as a mediator in this relationship. It is suggested that healthcare providers should prioritise the identification and management of diabetes distress in older patients with diabetes who experience loneliness to improve health promotion behaviours and optimise disease management outcomes

Effective disinfecting of negative pressure pipelines of DCUs reduces the risk of cross infection in dental care

ABSTRACTObjectives Microbial contamination of various accessory parts of the dental chair units (DCUs) is an essential source of cross infection, while the accessories of the crucial suction function are usually overlooked. In this study, we aim to find an effective disinfectant and a cost-effective method to remove bacterioplankton and bacterial biofilm deposited in the negative pressure suction pipelines to control cross infection during dental treatment.Methods Double-chain quaternary ammonium salt disinfectant (Orotol Plus®), 3% hydrogen peroxide solution plus multi-enzyme cleaning agent and chlorine disinfectant are used to clean and disinfect the negative pressure pipelines of DCUs. Microbiological examinations, air condition detection, corrosion tests and gene sequencing are performed.Results Little bacteria grow in the pipelines disinfected with double-chain quaternary ammonium salt disinfectants, destruction of biofilms in these pipelines appears, and multi-resistant bacteria cannot be detected. Minimal damage to metal sheets and fittings is caused by double-chain quaternary ammonium salt disinfectants.Conclusion Double-chain quaternary ammonium salt disinfectant has excellent bactericidal ability and anti-biofilm effect, and it is less corrosive to the fittings of the pipelines. Thus, the double-chain quaternary ammonium salt disinfectant is a potential novel disinfectant for negative pressure suction pipelines of DCUs to control cross infection during dental treatment.Clinical significance It is essential to add all these data to our dental practice to control cross infection with a broader landscape

Antibiotic treatment can exacerbate biofilm-associated infection by promoting quorum cheater development

Abstract Quorum cheating, a socio-microbiological process that is based on mutations in cell density-sensing (quorum-sensing) systems, has emerged as an important contributor to biofilm-associated infection in the leading human pathogen Staphylococcus aureus. This is because inactivation of the staphylococcal Agr quorum-sensing system leads to pronounced biofilm formation, increasing resistance to antibiotics and immune defense mechanisms. Since biofilm infections in the clinic usually progress under antibiotic treatment, we here investigated whether such treatment promotes biofilm infection via the promotion of quorum cheating. Quorum cheater development was stimulated by several antibiotics used in the treatment of staphylococcal biofilm infections more strongly in biofilm than in the planktonic mode of growth. Sub-inhibitory concentrations of levofloxacin and vancomycin were investigated for their impact on biofilm-associated (subcutaneous catheter-associated and prosthetic joint-associated infection), where in contrast to a non-biofilm-associated subcutaneous skin infection model, a significant increase of the bacterial load and development of agr mutants was observed. Our results directly demonstrate the development of Agr dysfunctionality in animal biofilm-associated infection models and reveal that inappropriate antibiotic treatment can be counterproductive for such infections as it promotes quorum cheating and the associated development of biofilms